Summer Vacation: Cruise Ship Health Risks

Schools are out and summer travel is in fulls swing as families prepare for holidays that they waited for all year. However, there are some health issues that should be considered before you head off to wherever your travels may take you.

General Cruise Vessel Health

Viruses are extremely tiny infectious agents that are only able to live inside a cell, and are the leading cause of major outbreaks on cruise vessels. The Centers for Disease Control and Prevention (CDC) warns that most viruses are associated with cruise ships due to close living quarters, unsanitary precautions, and infected passengers. Passengers touching many surfaces in concentrated areas increase the chances of a person catching a virus. The Vessel Sanitation Program (VSP) works to help stop the spread of viruses onboard. The CDC reports that in the past 10 years, the Norovirus, Legionnaire’s disease, and vector-transmitted diseases were most commonly contracted aboard cruise ship vessels. The VSP encourages travelers to learn how these viruses are transmitted, understand the health consequences, and be familiar with prevention and treatment.

The Norovirus

Noroviruses (previously known as Norwalk-like viruses) are a group of viruses that affect the stomach and intestines. They may cause gastroenteritis, an inflammation of the stomach and the large intestines, and may be contracted at any age. The symptoms of noroviral infection can sometimes be misdiagnosed as food poisoning. This human pathogen results in over 200 million annual infections worldwide. Outbreaks occur more often where there are more people in a small area, such as aboard cruise vessels. Noroviruses are found in the stool or vomit of infected people and on infected surfaces that have been touched by ill people and are highly contagious. The incubation period, the development of an infection between the time the pathogen enters the body and the time the first symptoms appear, is usually 24 to 48 hours after first exposure to the virus. Signs and symptoms usually last one to five days. The diversity within noroviral infection genus makes it difficult to control.

Transmission: Noroviral infection is highly contagious, so transmission can easily happen. One of the most common means of transmission is through eating contaminated food or drinking water. In May 2004, the VSP investigated an outbreak of norovirus gastroenteritis onboard a cruise ship sailing in Alaskan waters to identify a common food source item that caused the outbreak. In summer 2006, several cruise-related viral gastroenteritis outbreaks were reported in Europe. Two of these occurred on a river cruising vessel and were linked to tap water. This virus is transmitted by touching objects or surfaces that are contaminated and then touching one’s own mouth, nose or eyes, or by person-to-person transmission, such as shaking hands. It may also be transmitted by a lack of hygiene, such as keeping hands clean after using the bathroom or changing diapers, and then preparing or eating foods.

Symptoms: The most common symptoms of noroviral infections are vomiting, loose stool, and abdominal cramps. Other symptoms include low-grade fever, chills, headache, muscle aches, nausea, and fatigue. Sometimes infected people show no symptoms, but may continue to shed the virus via feces for several days, with potential for infecting others.

Prevention: The best way to prevent the spread of the norovirus is with thorough and frequent hand washing with hot water and soap. Passengers should wash hands after every trip to the bathroom, after every diaper change, and after preparing or eating food. Passengers should also avoid shaking hands of others, but use of hand sanitizers when available is recommended. The VSP and CDC work with vessel owners to develop Norovirus action plans, which include training of all employees and materials with instructions. These plans are designed to stop person-to-person transmission with disinfectants to kill these highly contagious pathogens. Private cabins and public areas are the places of greatest concern onboard. In addition, the CDC has created the Outbreak Prevention and Response Protocol (OPRP) to help control and prevent Norovirus transmission. The OPRP uses code yellow and code red to distinguish the level for threat of possible infection. In the case of a code yellow or code red, the vessel’s staff takes the appropriate actions, such as isolating passengers in cabins, using disinfectants, and evaluating passengers for symptoms. After the ship has returned to normal operations, a meeting is held to review which procedures went smoothly and which need modification.

Treatment:There is no treatment for Norovirus, but passengers who exhibit the symptoms of the virus should be evaluated by a medical professional. Treatment also focuses on alleviating symptoms while the body fights the virus. Because there is a chance that dehydration can occur, patients are often given fluids. Other treatment options include rest, abstaining from food for several hours and then slowly re-introducing mild foods, and avoiding foods and drinks that could upset the stomach or contribute to dehydration, such as caffeine and alcohol.

Legionnaires’Disease

Legionnaires’ disease is a serious and potentially fatal type of lung infection caused by a type of bacteria called Legionella. The bacteria got its name in 1976, when a group of American Legionnaires contracted it at a convention in Philadelphia, during which 34 of 221 persons died. Although this type of bacteria existed before 1976, since then, detection of Legionnaires’ disease has increased; each year, between 8,000 and 18,000 people are hospitalized with Legionnaires’ disease, and in the United States it continues to be a public health concern on passenger ships. The Legionella bacteria are found naturally in the environment, usually in water. Because they thrive in warm, moist areas, they may be present in hot tubs and air-conditioning systems. People over the age of 65 have the highest risk for contracting Legionnaires’ disease, as do smokers and those with lung deficiencies and weak immune systems. Detection of the disease is confirmed with urine and blood tests. Most of the time, patients can be successfully treated with antibiotics, and healthy people usually recover completely.

Transmission: Legionnaires’ disease is contracted by breathing water vapor, such as steam from a hot tub that has been contaminated with the bacteria. It cannot be spread from person to person. This disease can easily be transmitted to passengers with weak immune systems aboard cruise vessels with contaminated water systems. Drinking water, bathing water, spas and pools, and even air conditioning units within cabins may be contaminated. Pontiac Fever, a flu-like illness, may occur after contraction of Legionella bacteria. In January 2003, two cases of Legionnaires’ disease on cruise ships were reported to the National Epidemiological Surveillance of Infectious Diseases (NESID). One patient, a 70 year-old male heavy smoker with mild emphysema, contracted the disease in the ship’s indoor spa. Another patient on the same ship was a 73 year-old female. Environmental investigation revealed that absorbent natural stones in the filters of the spas had harbored bacteria that transmitted Legionnaires’ disease.

Symptoms:The symptoms of Legionnaires’ disease are similar to the symptoms of pneumonia. They include high fever, chills, cough, muscle aches, and headaches, and usually begin 2-14 days after exposure to the bacteria. Gastrointestinal symptoms such as diarrhea are also common. A milder form of the infection caused by the same bacteria is Pontiac Fever. Symptoms include a fever, headaches, and muscle aches, and usually subside after 2-5 days with no treatment. Most patients who have Legionnaires’ disease need chest X-rays to check for pneumonia.

Prevention: Cigarette smoking seems to be the most common risk factor in contracting this type of bacteria, so it is important for patients to quit smoking.Avoiding this disease can be difficult because it is spread through the environment, and not through personal contact. Demanding diligent disinfecting is a great form of preventative measure. Passengers should learn the history of the vessel on which they plan to travel and ask questions about air conditioning maintenance, disinfection of spas and pools, and history of outbreaks onboard. The VSP also requires that all vessels should disinfect all showerheads every six months to prevent the growth of Legionella bacteria.

Treatment: Antibiotics are the most effective way to treat Legionella bacteria.

Insectand Rodent Diseases

Minimizing the risk of vectors that cause diseases, such as insects and rodents, is also important. Mosquitoes, rats, mice, flies, and bedbugs are all potential transmitters of disease. Rats and rodents may be vectors of many diseases, such as rat bite fever and salmonella. The most common vector-transmitted disease is malaria, which is spread by mosquitoes and may be fatal.

Transmission: Ports pose the greatest risk factor to vessels becoming contaminated with disease vectors because they are constantly receiving deliveries and managing supplies from many other ports. Food items also attract many species of pests and parasites. Mosquitoes transmit malaria parasites to humans, in which the parasites attack the blood. Over one million people die from malaria each year because there is no vaccine. The mosquito carries the disease from one human to another. Also, many cases are attributed to travelers returning from parts of the world where malaria is prominent, such as Africa. Rat bite fever is also an infectious disease that could be a risk factor for travelers on unmaintained vessels. Rats or other rodents may become infected with either Streptobacillus moniliformis or Spirillum minus. Humans may become infected when either scratched or bitten by the infected rat, or when ingesting food or drink that has been contaminated with rat feces.

Symptoms: Typically, symptoms of malaria begin 10 days to four weeks after the initial mosquito bite, although they may appear as early as eight days or as late as one year. Symptoms include asymptomatic infections, fever, chills, sweating, headaches, muscle pain, anemia, and kidney failure. The severity of the symptoms depends on several factors, such as the species of infecting parasite and the patient’s acquired immunity and genetics. Fever in the first week of travel to a malaria-risk area is unlikely to result from malaria, but travelers who feel ill should seek immediate medical care. Symptoms of Rat bite fever occur 2-10 days after transmission. The most common symptoms include chills, a fever, vomiting, headache, and muscle and joint pain.

Prevention: Prevention is based on avoiding exposure to mosquitoes and taking antimalarial drugs if traveling to areas where malaria is common, such as Africa. There are several types of antimalarial drugs, such as doxycycline, mefloquine (Lariam®), chloroquine, and the combination of atovaquone and proguanil (Malarone®). Doxycycline is the least expensive anitmalarial drug. It is good for last minute travelers because the drug is started one to two days before traveling to an area where malaria transmission occurs. It is taken daily, but it cannot be taken by women who are pregnant or by children under eight years of age. It may upset the stomach and increase sun sensitivity. Chloroquine is a drug that is good for long trips because it is taken weekly. It is not good for a last minute traveler because it needs to be started 1-2 weeks prior to travel. It may also exacerbate psoriasis. The VSP recommends that cruise vessels use an Integrated Pest Management Plan, which involves training crew, monitoring areas of the ship that attract pests, surveillance, and the use of pesticides. The VSP encourages documentation of all items entering the ship for the presence of vermin. Vessels also use traps, glue boards, and bait stations onboard to catch insects and rodents. There are many things that passengers should do to prevent getting Rat bite fever, such as avoiding contact with rats or rat dwellings, hand-washing, and avoiding hand-to-mouth contact.

Treatment: In many cases, medication or the immune system eventually helps stop the infection. The CDC recommends that treatment be guided by three main factors: the infecting Plasmodium species, the clinical status of the patient, and the drug susceptibility of the infecting parasites as determined by the geographic area where the infection was acquired. The drugs used for prevention are also used for treatment. These drugs are active against the parasite that forms in the blood. Other drugs that are used include Fansidar® and Lariam®. Fansidar® may have severe or fatal side effects. This drug must be discontinued if there is the appearance of a skin rash or occurrence of active bacterial or fungal infections. Lariam® was invented by the U.S. Army and is routinely given to soldiers overseas. Lariam® may cause neuropsychiatric adverse effects. Rat bite fever can be treated with antibiotics. Penicillin is the most recommended antibiotic, but erythromycin may be prescribed, as well.

Salmonella

Salmonella are bacteria that cause infection. Salmonella are a group of bacteria that may cause diarrheal illness in humans. The illness usually lasts 4- 7 days, but in more severe cases it may be fatal. The elderly, infants, and people with weak immune systems are more likely to have severe cases. The bacteria live in the intestinal tracts of humans and animals, including birds.

Transmission: Salmonella are transmitted to humans by eating foods contaminated with animal feces. The contaminated foods usually look and smell normal and are often of animal origin, such as beef, poultry, milk, and eggs. However, any type of food may become contaminated. Food may also become contaminated by the hands of an infected food handler onboard who did not wash his or her hands with soap after using the bathroom.

Symptoms: Most persons infected with Salmonella develop diarrhea, fever, and abdominal cramps after infection. In some cases, the diarrhea may be so severe that the passenger needs to be hospitalized. Some people may develop Reiter’s syndrome, which leads to pain in their joints, irritation of the eyes, and painful urination. This can last for months and sometimes years, and can lead to arthritis.

Prevention: There is no vaccine to prevent Salmonella poisoning. Passengers should avoid eating raw or undercooked foods. Food handlers should avoid cross-contamination of foods by keeping uncooked meats from produce and cooked foods, and hand-washing between handling different food items. Infected people should avoid preparing food and pouring water for others.

Treatment: Salmonella infections can usually resolve in days without treatment. Oral fluids are recommended for dehydration. Antibiotics, such as ampicillin or ciprofloxacin, are used if the infection spreads to the intestines.

Seasickness

Seasickness is a form of motion sickness caused by the motion of a floating platform, such as a ship, boat, or raft. Seasickness is characterized by nausea and, in extreme cases, vertigo, which is a balance disorder. It is brought on by the rocking movement of a ship or boat, and visual confusion when objects move with the ship. The severity of seasickness is influenced by the irregular pressure of the bowels against the diaphragm as they shift with the rising and falling of the ship.

Prevention: Passengers should avoid alcohol, fat and spicy foods to prevent seasickness. They should also avoid small spaces, participate in onboard activities to occupy the mind, stay in fresh air and take deep breaths, drink plenty of water, and get a good night’s sleep the day before boarding.

Treatment: Over-the-counter medications are available, such as Dramamine®. Ginger capsules or crystallized ginger is also recommended for settling the stomach. Passengers experiencing seasickness should try to focus their eyes on the fixed horizon. They may also try lying down on their backs and closing their eyes.